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G CEXO
2nd Oct 2008, 22:25
Can someone help me with a good rule of thumb for calculating the amount of wind increasing and decreasing by altitude ( from surface to say 2000ft )

I know wind will veer with increase in altitude and back with decrease in altitude, but by how much??

Please help :{

G-XO

Nipper2
2nd Oct 2008, 22:58
Compared to the 'official' 10m wind, 30% stronger and 30 degrees veered (+30) at 1000 feet is a good rule of thumb assuming unstable well mixed air.

But it could be completely rubbish on a day with high stability (or for any one of a host of other reasons).

And the wind may well be much less at 2 or 3 metres off the ground (the bit you are landing in).

JohnGV
3rd Oct 2008, 01:56
There is no rule of thumb! its not like temperature lapse rates - which arent even accurate anyway(mostly for engineering and met vague calulations).

the weather and wind particularily depends on so many different variables. u can never tell. it varys from day to day, hour to hour and minute to minute.

markp123
3rd Oct 2008, 17:04
yea, i'd agree that there isn't much of a useful rule for that as you probably well know it varies with speed and direction constantly throught the day and night.

but what's given in the Met syllabus as a "rule of thumb" for this is that from 2000ft AGL to the surface the wind backs by around 30 degrees and speed drops to about 50%. ...only applies overland though dut to friction layer...is a seperate one for over sea.

Cusco
3rd Oct 2008, 17:41
Exactly:

A rule of thumb is a useful approximation:

Not a rule of mathematical certainty.

30 degrees and fifty percent works well.

Who ever said that Met was a precise science.

Cusco.

ShyTorque
3rd Oct 2008, 19:53
Here's a link to a good rule of thumb:

Met Office: Online services - customer login (http://secure.metoffice.com/aviation/aviationProduct.do?productId=2110)

IO540
3rd Oct 2008, 21:12
From surface wind to 2000ft wind, I add 20kt and 20 degrees.

Whopity
4th Oct 2008, 08:44
Wind strengths and headings Wind may have Direction or even Track but never Heading!

G CEXO
4th Oct 2008, 21:20
Wind may have Direction or even Track but never Heading!

Sorry, I should have known better. I'm now going to Slit my wrists :ugh:

Thanks very much guys, I passed today with 90%. :ok: So thats 3 exams done and hopefully another 2 by the end of this month.

G-XO

JohnGV
5th Oct 2008, 06:54
G-CEXO,

sorry for polluting your thread. i just cant stand some of these absolute idiots on here!

Well done for passing! goodluck and keep doing well!

JV